The method described herein is applicable to the removal of metal alkaryl sulfonates from a hydrocarbon solution of the sulfonates. A typical hydrocarbon which is contaminated with such sulfonates is petroleum crude oil.
Aqueous solutions containing metal alkaryl sulfonates are used in the enhanced oil recovery (EOR) of petroleum crude oil from subterranean formations. The petroleum crude oil is recovered concurrently with an aqueous phase and after the separation of the aqueous phase from the crude oil, a substantial amount of sulfonate remains in the crude oil portion. The crude oil may be contaminated with sulfonates in an amount from about 10 to 5000 parts per million by weight, or more. The metal alkaryl sulfonates are often referred to as surfactants. The metal alkaryl sulfonate which contaminates the recovered crude oil must be removed or substantially reduced before the crude oil undergoes any further refining and processing. The presence of sulfonate in the crude oil during subsequent processing may cause corrosion, environmental pollution and/or hydrorefining catalyst poisoning.
Since enhanced oil recovery is becoming widespread in the oil production industry, the problem of surfactant contaminated crude oil is well known. Candor compels the acknowledgment that those skilled in the art are working in many directions to solve the problem. For example, U.S. Pat. No. 4,274,943 (McClaflin) teaches a method for the removal of metal alkaryl sulfonates from a hydrocarbon solution thereof which method comprises (a) contacting the hydrocarbon solution containing metal alkaryl sulfonates with an aqueous basic solution containing a "recovery" surfactant, (b) forming a hydrocarbon phase and an aqueous phase containing metal alkaryl sulfonates and (c) separating the hydrocarbon phase and the aqueous phase. U.S. Pat. No. 4,274,943 is one method which the prior art utilizes to separate or extract metal alkaryl sulfonates from recovered petroleum crude oil and is incorporated herein by reference thereto.
We have discovered a novel and effective method of removing metal alkaryl sulfonates from hydrocarbons including petroleum crude oil. The method of the present invention will be described in detail hereinafter.